he's dedicated himself to education. he's founder of the khan academy but his youtube channel has over 3,000 educational videos on everything from physics to history. his new book is titled "the one world schoolhouse." he's also on "time" magazine's list of 100 most influential people in the world. welcome. you are the most popular teacher in the history of planet earth. it's undeniable. the stats don't lie. is it four million people now watched your video lessons for want of a better phrase, right? >> that's right. seven million. we're not just videos, we have interactive exercises. it's not just me anymore. >> seven million people around the world will go online to see you give effectively a lesson. >> i give lessons, we have a few other folks who are doing it. we also have an interactive platform. it's all of the above. our team is 36 people. it's not seven million just for me. >> stop being so modest. this is not what you're here for. this is to celebrate you. it's a fascinating proposition. i've got three teenaged s